Mr. Coe went from being an unknown to a household name on Sunday night during the broadcast of the Academy Awards. He was in a group from a tour bus directed into the auditorium to rub elbows with Hollywood A-listers as cameras beamed the passengers’ shock and confusion live to the world.

He gamely kissed Nicole Kidman’s hand and shook hands with Ryan Gosling. Social media celebrated this Everyman dressed in tourist attire (baseball cap and hooded sweatshirt) who came face to face with celebrities dressed in their red-carpet finest.

Twitter lit up with delight.

Alas, the glow of Mr. Coe’s instant celebrity dimmed in less than 48 hours amid reports that he had been released from prison three days before appearing on the show.

But in the easy-come-easy-go world of fame and the internet, others came to his defense and expressed concern that he was being harshly judged.

Darlene Hill, a reporter for a television station in Chicago, wrote on Facebook, “More proof that ‘EVERYONE’ HAS A PAST — (including me) but IS THIS FAIR.”

She added: “He was celebrated and called ‘The Mayor of Chicago’ now Gary is LOSING SOME ‘LIKES.’ He hasn’t lived in Chicago in 25 years, spent 20 years in prison and there are reports that he was released just days before going on that tour. Some say, he did NOTHING WRONG, he’s served his time and was just minding his own business when he was thrown into the SPOTLIGHT.”

Others asked how his past was relevant to what happened at the awards ceremony and said Mr. Coe was one of the highlights of the show.

Mr. Coe was imprisoned for 20 years under California’s “three-strikes” law, which carried a mandatory a sentence of 25 years to life after an offender’s third conviction, The Chicago Tribune reported.

He was given the sentence after being convicted of petty theft in 1997 for stealing perfume; that conviction came after two grand-theft and two shoplifting convictions, The Tribune reported, citing court records. He also was convicted of burglary in Illinois in 1991.

Mr. Coe, 59, who could not be reached for comment, also appears on the California website of registered sex offenders for a 1978 conviction of attempted rape by force or fear. His public defender in Los Angeles, Karen Nash, said in a post on Facebook on Tuesday that the charge was from 1975, when he was a teenager.

In a separate post on Monday, she wrote: “For those of you who missed it — I spent years working on Gary’s case. He got a life sentence for stealing perfume in 1997, and we finally won release this year. He got out on Friday, and was sightseeing with his lovely fiancé Vicky. If you watched the Oscars, you know the rest.”

In an interview on Tuesday night, Ms. Nash said she had talked to Mr. Coe every day since the broadcast and described him as upbeat.

She said Mr. Coe and his fiancée are “a little bit overwhelmed.”

“He doesn’t hear negativity,” she said, adding that he is looking forward to being a mentor to others who need help.

“Mostly,” she said, “he just wants to get get a job and get on with his life with Vicky.”